Heretofore, it has been proposed to provide electric motor driven lift mechanisms adapted for use in moving a platform or the like vertically between at least two spaced positions. Certain of such mechanisms include followers adapted to travel lengthwise of a pair of parallel upstanding guide shafts; a nut coupled to an upstanding, threaded drive shaft adapted to be driven for rotation in opposite directions by an electric motor; and trip or operating fingers arranged to trip or operate stationary limit switches, which alternately serve to de-energize the electric motor upon placement of the platform in its vertically spaced positions. Patents disclosing lift mechanisms of this general type include, for example, U.S. Pats. Nos. 1,986,620; 2,895,567; 3,215,402 and 3,993,008.